Field of the Invention
The present invention relates to an image forming system.
Description of the Related Art
In recent years, series-connected tandem image forming systems in which two image forming apparatuses are connected in series for two-sided printing and the like have been in practical use (refer to JP 2005-022243 A, for example). For example, a primary image forming apparatus (primary apparatus) forms an image on a front face of a sheet, and a secondary image forming apparatus (secondary apparatus) forms an image on a back face thereof. This enables improvement in productivity as compared to a case where two-sided printing is performed by one image forming apparatus. Such series-connected tandem image forming systems are typically applied to the field of production print where higher productivity is sought.
JP 2005-022243 A discloses an image forming system capable of total management through sorting of printed recording media into one-sided printing and two-sided printing without lowering the processing efficiency of one-sided printing and two-sided printing.
Furthermore, JP 2001-502813 W does not disclose a series-connected tandem image forming system but discloses an image forming apparatus including two conveyance paths for conveying sheets, and image forming units disposed on the two conveyance paths and configured to form images on the sheets. With the image forming apparatus disclosed in JP 2001-502813 W, even in a case where a failure occurs in one of the image forming units, an image can be formed on a sheet by the other image forming unit.
The aforementioned series-connected tandem image forming systems, however, are disadvantageous in that the entire image forming system halts and printing is disabled in the event of occurrence of a problem in image formation in either of the two image forming apparatuses, such as a failure of the printed control board for controlling the image forming process, or a paper jam.
JP 2005-022243 A mentioned above teaches a measure for two-sided printing even if a failure occurs in either of the first printer and the second printer, but has another disadvantage in that two sheet discharging devices (first sheet discharging device and a second sheet discharging device) are required for this measure, which results in an increase in size of the image forming system.
Furthermore, the technology disclosed by JP 2001-502813 W mentioned above relates to one image forming apparatus and cannot solve the disadvantages relating to the series-connected tandem image forming system.